Mesophilic mutants of an obligate psychrophile, Micrococcus cryophilus

1969 ◽  
Vol 15 (10) ◽  
pp. 1145-1150 ◽  
Author(s):  
P-C. Tai ◽  
H. Jackson
Keyword(s):  
Growth Temperature ◽  
Metabolic Pathways ◽  
Thermal Denaturation ◽  
Deoxyribonucleic Acid ◽  
Elevated Temperatures ◽  
Maximum Growth ◽  
Maximal Growth ◽  
Denaturation Temperature ◽  
Maximum Growth Temperature ◽  
Thermal Denaturation Temperature

Several mutants with elevated maximal growth temperature (MGT) were developed from an obligate psychrophile, Micrococcus cryophilus ATCC 15174, by ultraviolet irradiation. Two of the mutants, T8 and M19, have the most similar characteristics to those of their parent. The mutants lost the ability to grow well at 0 °C and showed changes in metabolic pathways while acquiring the ability to grow at elevated temperatures. Heat resistance and deoxyribonucleic acid thermal denaturation temperature were shown to be unrelated to maximum growth temperature. The significance of the mutants is discussed.

The effect of temperature on lysis of cells and cell walls of Bacillus psychrophilus

1971 ◽  
Vol 17 (9) ◽  
pp. 1161-1168 ◽  
Author(s):  
Stephen J. Mattingly ◽  
Gary K. Best
Keyword(s):  
Cell Wall ◽  
Growth Temperature ◽  
Cell Walls ◽  
Elevated Temperatures ◽  
Maximum Growth ◽  
Zero Order ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Maximum Growth Temperature ◽  
Cell Wall Lysis

Cells of Bacillus psychrophilus lysed rapidly when suspended in carbonate or phosphate buffer at a temperature above the maximum growth temperature (30C). This lysis was found to be temperature dependent. The effect of various inhibitors of whole cell lysis was examined. D-Serine, CaCl2, sucrose, and polyethylene glycol were found to be quite effective in inhibiting lysis at 37C. However, this inhibition seemed to be nonspecific. Lysis of isolated cell walls of this psychrophile was also found to be temperature dependent. Lysis was linear and zero order throughout the growth range of this organism. However, as the temperature was increased (37 and 45C) the rate of lysis increased rapidly and zero-order kinetics was lost at these elevated temperatures. D-Aspartic acid was the most effective inhibitor of cell wall lysis. However, its action was only apparent at temperatures above the maximum growth temperature. These results suggest that the cell wall of B. psychrophilus is unusually heat labile and indicate a novel mechanism of lysis.

scholarly journals Growth Temperatures of Ropy Slime-Producing Lactic Acid Bacteria

1990 ◽  
Vol 53 (9) ◽  
pp. 793-794 ◽  
Author(s):  
HANNU J. KORKEALA ◽  
PIA M. MÄKELÄ ◽  
HANNU L. SUOMINEN
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Growth Temperature ◽  
Meat Products ◽  
Maximum Growth ◽  
Meat Processing ◽  
Continuous Growth ◽  
Maximum Growth Temperature ◽  
Processing Plants ◽  
Cooked Meat

The minimum, optimum, and maximum growth temperatures of ropy slime-producing lactic acid bacteria able to spoil vacuum-packed cooked meat products were determined on MRS-agar with temperature-gradient incubator GradiplateR W10. The minimum growth temperatures of slime-producing lactobacilli and Leuconostoc mesenteroides strain D1 were below −1°C and 4°C, respectively. The low minimum growth temperature allows these bacteria to compete with other bacteria in meat processing plants and in meat products causing ropiness problems. The maximum growth temperatures varied between 36.6–39.8°C. The maximum growth temperature of lactobacilli seemed to be an unstable character. Single lactobacilli colonies were able to grow above the actual maximum growth temperature, which is determined as the edge of continuous growth of the bacteria. The significance of this phenomenon needs further study.

Similar C-phycocyanins from two strains of thermotolerant cyanophyte Mastigocladus laminosus

1977 ◽  
Vol 23 (5) ◽  
pp. 510-517 ◽  
Author(s):  
Oranda H. W. Kao ◽  
Donald S. Berns
Keyword(s):  
Elevated Temperature ◽  
Thermal Denaturation ◽  
Ph Value ◽  
Blue Green Alga ◽  
Denaturation Temperature ◽  
Mastigocladus Laminosus ◽  
Thermal Denaturation Temperature ◽  
Temperature Ranges ◽  
Synechococcus Lividus ◽  
Immunologic Properties

C-phycocyanin from two strains of the thermotolerant blue-green alga, Mastigocladus laminosus (NZ-DB2-m and I-30-m), that grow within different temperature ranges have been characterized with respect to aggregation, immunologic properties, subunit composition, and thermodenaturation. The critical thermal-denaturation temperature for phycocyanin from both strains of M. laminosus phycocyanin is 60 °C which is higher than that for mesophilic phycocyanin. Immunodiffusion studies have shown that these two strains of M. laminosus exhibit no antigenic differences and are closely related to the mesophilic Plectonema calothricoides and the thermophilic Synechococcus lividus (strain 3). Neither phenol nor α-naphthol has any effect on phycocyanin aggregation in these two strains of M. laminosus. There is also no enhancement of formation of large aggregates at their elevated temperature of cultivation. Furthermore, the phycocyanin of both strains of M. laminosus does not demonstrate any large amount of 19S or higher aggregates at any pH value. These observations suggest that the mode of adaptation of M. laminosus phycocyanin to high temperature is different from that previously encountered. It is also important to note that phycocyanin is essentially unchanged whether it is extracted from the same strain, M. laminosus (NZ-DB2-m), grown at either 50° or 37 °C.

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